CPE Weird Print result

[stan_bulgaria 4]

Hello guys,

 

Let me apologize for the long introduction first.

 

I'm completely new to 3d printing. For the last 3 weeks I've been reading Cura tips and Youtube clips how to set my (slicer to slice the) model for a nice looking print result. My printer is Ender 3 V2.

 

I have a detail, part of an anemometer which I printed with the standard PLA filament that came with the printer. The result was satisfactory. Since some elements of the detail are very thin I encountered "warp" and "stringing". Meanwhile Cura 4.8. came to existaence so I updated some of the settings to fix the problems.

But since the detail has to work in "difficult" environment I chose to use CPE for the final print. The filament is Fillamentum CPE HG100 Black soul. 

 

I wanted to print a test sample of part of the detail before going for all of it in order to set the printer correctly. Here is where the problems started.

1. Print temperature -

- With the PLA filament I printed at 200 degrees. The initial setting was for 210 degrees but at 200 it had less stringing and printed fine.

- So based on the PLA experience I set the temperature for CPE HG100 to 255 degrees.

2. Plate temperature - I selected 77 degrees.

3. Fan - 70% = 178 rpm

4. In the attached .3mf file you can see the detailed settings.

The result of these settings was disaster. Everything was full of stringing. The model detached from the plate when it reached height of 7-8 mm with the raft. It happened due to material that stuck on the nozzle. I was not watching it at that moment, so no idea was it from the strings that got around the nozzle or some extra material in the infill.

 

In any case I repeated the trail with new settings of the temperature.

 

I wanted to find out what is the temperature at which the filament starts to drop from the nozzle. The working temperature recommended by the producer is 255-275 degrees. Heated bed - 70-85.

 

It appeared that the filament started extruding freely between 210 and 215 degrees. But it was not an uniform string. It had bumps (like balloons) which normally should appear when the material is with humidity (if I understand it well). Well the filament I opened just before I started the first settings print. Room temperature - 19 degrees; humidity - 49%. So humidity should be excluded (otherwise bad advertisement :-)

I've noticed that when I feed more material the string through the nozzle is perfect at 215 degrees !? More pressure to the extruder gives better results.

 

Second trial with corrected settings.

1. Nozzle temperature -215

2. Bed temperature - 100

3. Fan speed - 125 rpms

4. Raft wider to 6 mm.

Result: Almost immediate debonding of the raft.

 

So I started increasing the nozzle temperature at 10 degrees steps.

The result was the same. Then I kept the nozzle temperature to 235 and reduced the bed temperature to 70 and the fan speed to 100. Actually the fan speed at the first 4 layers - which are the raft is 0.

 

So the final result for the material to stick to the bed was:

1. Nozzle T=245

2. Bed T=70

3. Raft fan speed 0.

 

But then came the next problem. At this setting there was full of stringings. So a new fine tuning while printing: Nozzel T=235; Bed T=70; Fan speed =190. No stringing. I'm happy. Not for long unfortunately.

 

New problem. As you will see on the pictures of the detail, at about 9-10 mm height the material started building at one of the edges and got the nozzle sticked to it, so it debonded the element from the bed and ruined everything.

 

Now what is noticeable of the picture is the edges of the elements which are full with "bubbles" or "bumps". At 255 degrees they were severe and the whole surface was full with them. At 235 they are on the edges and on some spots of the "outer" side (the wider) of the element. They are spread randomly.

 

I know someone will say the temperature is very low and not correct. I agree, but the test shows that the imperfections are more at higher temperature (I missed to write that at higher temperature the stringing is enormous). The bonding of the layers seams strong - I tried to get a string from the last layer printed. It is not possible.

 

Questions:

1. Is the reason for the bumbs on the surfaces the "Coasting" setting in Cura? Or "Z seam alignment", checked as RANDOM? Both are ON.

2. Is the reason for the bumbs on the edges "Filter out tiny gaps", which is ON? Or "Compensate wall overlaps", also ON?

3. May be it is "Combing" also ON?

 

I cannot see the reason on the model in the slicer. All logic is that there should be no stringing and no warp. But I get stringing and bumbs.

 

P.S. I missed to mention that the nozzle was cleaned before every new settings - on the outside! It got material there (probably for the collisions). Very weird!

 

Thanks for you attention.

Stan

Anemometer Test.gcode CE3PRO_Anemometer Test.3mf

[stan_bulgaria 4]

Hello again guys,

 

here is an update to the above story. Attached are pictures from new print that again failed. I switched off the combing but the result was the same. You can see it on the pictures. The rest of the settings were the same. 

I checked again the model I printed with PLA. Yesterday I was wrong. Similar imperfections can be seen on the edges of the sphere parts (shells). They are not that severe like with the black CPE but also exist.

 

Two differences in the two models - the white "shells" are with 1 mm thickness and the black - 2 mm. Pay attention that this thicknesses are at plane (layer) parallel to the base of the printer. On every other layer the thicknesses are a bit more - 0,01 mm and up. This lead to some extra infill overlapping - the set value is 0,1 mm but in reality the second path of the nozzle is covering the first almost 95%. Why is that? I guess the reason is the geometry of the model. At thickness 2 mm and nozzle 0,4mm there should be 5 paths. But this must happen only at the layer exactly in the middle of the model. Every other layer must have 6 moves to compensate the left 0,01 or so gap. Am I correct? If yes what do I have to do to solve this issue?

 

Another thing I've noticed but I explain it in the video attached.

https://youtu.be/rSDe5XlUYT4

 

The white "shell" was one piece but I dropped the model and it broke. The plane that it split was not extruded correctly - the layer was a bit moved off the surface. The other two "shells" of the model doesn't have that defect. There are 3 "shells" in the model.

[geert_2 557]

I don't know your materials, but in my experience PET tends to ooze out and string more than PLA: molten PET is more rubbery than PLA, which is more like yoghurt.

 

I see different types of blobs in my PET-prints:

- Those that ooze out while traveling through air, and are then deposited onto the next wall, often forming "insect antennas". Printing slower helps, because then less pressure builds up in the nozzle, and thus less molten material leaks out.

- Material that accumulates on the outside of the nozzle, and then sags and gets dropped on the print, often in big lightbrown blobs. Oiling the hot nozzle with PTFE oil reduced that effect, then it becomes more like a teflon cooking pot. This is not an official method, just my own.

- When printing very small items, the hot nozzle stays on top of a tiny area, so the print can not cool down and solidify: thus it stays molten and deforms into blobs. Printing cool and in thin layers helps, and multiple parts (but then you get the oozing while traveling).

- Without cooling, overhangs are difficult: the molten material does not pull into a string, but snaps and folds back onto the nozzle, like a rubber band snapping. That causes blobs too, looking a bit like tiny grapes. More cooling reduces this, but gives worse layer bonding.

 

In general, for PET: printing very cool, at the lowest edge of the temp range for that material, and in thin layers, and slow, gives the best results for me.

 

Also see my photos of PET test blocks in my reply of yesterday here:

 

This is the effect of printing small items: the nozzle stays on top of it, too hot, so it can not solidify. Printing a dummy tower next to it, or multiple parts at once, reduces the effect.

 

 

[stan_bulgaria 4]

Thanks for the suggestion Geert. What you point has a lot of logic. I'll give it a try an come back with update.

[stan_bulgaria 4]

Update.

Start settings for the raft: Tn=245; Tb=75; Fan=0; Speed=15 mm/s

When the model starts print: Tn=215; Tb=75; Fan=210; Speed=30 mm/s

 

The edges of the left of the elements started bending up. After 2-3 layers the nozzle hit it, naturally. The other element edges were fine - not bended upward. The two elements are at 120 degrees positioned and the nozzle moves are not the same relative to their axes.

 

Apparently the problem is finding the proper temperature and fan speed. The blobs were a few this time.

 

So, more trials to find the truth.

[stan_bulgaria 4]

One more thing.

 

In order for the raft to stick to the bed the combination proven working for me, is as mentioned above:

 

Tn=245; Tb=75; Fan=0; Speed=15 mm/s

 

Higher bed temperature or low nozzle one is debonding the raft, at least for this CPE.

[stan_bulgaria 4]

Hello again,

 

After a new set of tests the result can be seen on the pictures. That was achieved at:

Tn=225

Tb=75

Fan=191 rpms

Speed=30mm/s

 

I managed to reach 5-6 mm height excluding the raft. At his height the element debonded from the raft but due to some very short and frequent moves of the nozzle, that shaked it strong. That moves can be seen on the attached pictures from #64 to #73. Layer #74 is what can be seen on pic ...103516. That problem will be overcome with extra support I'll have to input in the model.

 

Another question is how to change the temperature during the print from Cura settings, but I'll make it in a new post.

That is because I used different T settings along the height of the printing. I started the raft as described above:

Tn=245

Tb=75

Fan=0

Speed=15 mm/s

I have waited 10 minutes after reaching the specified temperatures to have constant settings. Then checked the leveling. Cleaned the material that was coming from the nozzle. Refilled the new filament. Started.

 

The raft settings I made manually through the tune settings of the printer. After the raft was finished the printer corrects the T to the specified settings in Cura. I override them manually again to set as:

Tn=240

Tb=75

Fan=125 rpms

Speed=30 mm/s

 

After 4-5 layers new fine tuning:

Tn=235

Tb=75

Fan=191 rpms

Speed=30 mm/s

 

Final tuning after another 4-5 layers:

Tn=225

Tb=75

Fan=191 rpms

Speed=30mm/s

 

This settings are not close to the filament producer suggestions, but for my case are the working ones.

 

 

[stan_bulgaria 4]

Something went wrong with the pictures. The first two are the last layers before the collapse.

[Torgeir 242]

Hi Stan,

 

This is a very challenging print not just for your printer, but for any fdm 3D printer.. 🙂

I've no experience with your type of printer, but there is some common thing that's might improve a little.

As there is very "marginal" first layer, or better - solid bed attachment for some parts of your print object.

So decrease support angle to at least 45 deg (your project 63 deg) in order to have some more support and you may also increase support density say from (5 to 10)% or even more.  As the model climb higher, the mass off the object increase and "center of gravity" CG arm also increase for this part. If this go on with high speed (50 mm/s), the force produced by the accelerating heat bed (Y axis) might be high enough to tear the object off the heat bed.

So I would go down to half of the speed for all tree speed settings as a try -say 25 mm/s.

Another thing that's may improve the surface of the object is to set Z seam to sharpest corner. This shoud make some better surface of your print.

Last thing is the retraction setting for your printer, this also is a key tool for blobs and stringing among -temp setting fan setting fine tuning.

This latter thing is some settings thats depend of your printers proprties I cannot answer.

 

Good luck

 

Thanks

Torgeir

 

 

Edited November 26, 2020 by Torgeir
Text error.

[geert_2 557]

If I had to print this model, I would consider one of two options:

 

1. Split the model in half, top and bottom, print both halves separately, and glue or bolt them together. In case of bolting, provide holes for inserting bolts and nuts. I often use standard nylon M4 for most of my designs that need to be assembled and disassembled.

 

2. Design a custom support and brim in CAD, so it fully supports your model where you want. If well done, it should print better, give less deformations. But it will cost time and may take a bit of trial and error. If you leave a tiny gap between your custom support and the model, it will still bond enough, but be easy to remove. Also, you could redesign the bulbs and stems to print better, with less steep overhangs. See these quick concept-drawings of a bulb with custom support, oval bulb with less steep overhangs, and a stem with less steep overhangs and support. The gap between support and model will be trial and error: try one bulb and stem until good, before doing a whole print.

 

 

 

[stan_bulgaria 4]

Hello Torgeir,

 

thank you for your reply.

 

I fully agree with your suggestions. I understand that these "shells" are challenge to be printed.  Especially in the positions I had placed them. The fact is they are three for the detail. At the beginning I have included supports on the back side of each one. But when printing the model with the white PLA and the support that Cura made for them was fine, so I removed mine.

One thing I have to admit. The original shells were 1 mm thick and the black CPE are 2 mm. Obviously the extra thickness is playing big role.

I decreased the support angle to 45 and will give it a try tonight.

 

Another thing I haven't check yet is to rotate the model so no shell face is parallel to X or Y axles. May be that way the vibrations will not have so significant role.

 

Regards

Stan

[stan_bulgaria 4]

Thank you Geert,

 

I didn't know of that trick with the gap. I made my own support that I removed but will put it back again, only with a gap of may be 0,5 mm.

 

Regards

Stan

[Torgeir 242]

Just forgot one thing..

As the bed is moving the print object, it might be a much smoother ride if the acceleration is decreased.

Just to mention.

 

Torgeir.

[stan_bulgaria 4]

I haven't check this setting.

Now I put it ON and all the values are 500 mm/s2. Isn't that too much?

[Torgeir 242]

If this is the normal setting, I would only reduce the bed (if I'm right, it's Y?)..

How much? Don't know, but 25% less should do some changes..

 

🙂

 

[stan_bulgaria 4]

OK. I'll do the changes one by one so I know what the efect is.👍

[geert_2 557]

41 minutes ago, stan_bulgaria said:

Thank you Geert,

 

I didn't know of that trick with the gap. I made my own support that I removed but will put it back again, only with a gap of may be 0,5 mm.

 

Regards

Stan

 

Not sure, but I think a gap of 0.5mm might be a little bit too big? Maybe make a small test piece with gaps of 0.1, 0.2, 0.3, 0.4, and 0.5mm. Print that and compare what works best for you? It will also depend on the material, cooling, printing speed, printing temp: obviously, hotter will melt things more together. It will also depend on the width of your support: wider will be more difficult to remove. I usually take "one nozzle-width" for such supports (thus 0.4 to 0.5mm wide for a 0.4mm nozzle): that is still easy to cut off. And gaps between 0.2 and 0.4mm, depending on the model. My fixed rule is that there is no fixed rule.  :-)

 

[stan_bulgaria 4]

1 minute ago, geert_2 said:

 

Not sure, but I think a gap of 0.5mm might be a little bit too big? Maybe make a small test piece with gaps of 0.1, 0.2, 0.3, 0.4, and 0.5mm. Print that and compare what works best for you? It will also depend on the material, cooling, printing speed, printing temp: obviously, hotter will melt things more together. It will also depend on the width of your support: wider will be more difficult to remove. I usually take "one nozzle-width" for such supports (thus 0.4 to 0.5mm wide for a 0.4mm nozzle): that is still easy to cut off. And gaps between 0.2 and 0.4mm, depending on the model. My fixed rule is that there is no fixed rule.  🙂

 

I like your final words.😃

[stan_bulgaria 4]

Hello folks,

 

step by step there is some progress. You can see it on the pictures.

 

I've reached height of 10 mm without the raft height. I little change on the settings was made. The initial settings were as above. The difference is that I changed the support angle to 45 degrees. To lower the vibrations of the bed made during the infill I reduced the speed to 80% from the original 30 mm/s and because of this increased the fan, since stringing started to appear.

One thing is with no doubt affecting the print quality as surfaces and print stability - the orientation of such details on the print bed. You can see the bottom of one of the "shells" is nice and smooth, while the other one is like skipping layers. However going up the Z axes has vice versa effect!? Anyway the final surfaces will be smoothed mecanically.

 

Today I'll add the support as Geert adviced.

[geert_2 557]

8 hours ago, stan_bulgaria said:

Hello folks,

...

Today I'll add the support as Geert adviced.

...

Yes, but don't do the whole model yet. Do a small test part: let's say only one bulb, attached to a short stem. And that with different gap-variations. See which gap works best. Then you will lose the least amount of time and material.

 

[stan_bulgaria 4]

Geert, I've read some of your posts regarding the warping and the bed adhesion - very good technics.

 

After I decided to print the whole detail, since that the temperature settings will have totally different effect, I came up to the attached crashing result. Please don't laugh on the adhesion decicion as what happen was warping or bending at a height of 10 mm. More severe it appeared after I debonded the final "thing" of the bed. 

 

The bottom side raft surface is like a mushroom or like lens. Right in the center of the detail is the pick of the lens.  The edges, where the shells end, are lifted from 3 to 6 mm. Huge bending. I doubt such a stress in material can hold it to the bed. I saw it when it started debonding from the bed and put that cable insulation tape. I knew the result would be disastrous but I was curious. So with every bending I was sticking the parts with tape.

 

Now I'm thinking what is wrong.

For the next print:

1. I changed the wall thickness and counts to get rid of the infill moves in the shells that are making to much vibrations.

2. Removed the gap of 0,4 mm between the raft and the first layer so they stick better.

 

Here is the question. Should I turn off the heat off the bed after I print the raft in order to have more uniform temperature along the whole structure of the model? The fan speed was 205 rpms and I almost didn't have any stringing and blobs were minimum. Nozzle T=225 and bed T=75, but reduced to 70 after first debonding. The room temperature was 20 C humidity 46%.

 

Thanks again.

[stan_bulgaria 4]

To clean the bed I use paint solvent which main ingredients are:

Toluen - 50-60%

Xylene - 10-20%

Acetone - 10-20%

n-butyl acetat - 5-10%

 

I always use this solvent to degrease and clean surfaces before fine painting with resins and it gives very good result. It is very strong, however it dissolves some plastics and even harden resins.

[geert_2 557]

I don't know your filament, nor your printer and print-bed, so it is very hard to give advice on what bonding methods and preparations you could use.

 

But the chemicals you are using, are toxic and cause cancer, especially xylene. Some of my previous collegues got cancer after using xylene carelessly for years, against all our safety-advice. So use them carefully in well ventilated rooms, and don't touch them. Preferably look for non-toxic stuff, or less toxic.

 

I have glass beds, and most of the time I never clean them: I just wipe them with salt water, and go. For my PLA prints this works well. If the glass is greasy, I clean it with isopropyl alcohol first, and then with pure tap water. (No soap, no detergents, no window cleaner, no thinner,...: they often reduce bonding.) But that might not work for you.

 

I leave the heated bed on, because otherwise the PLA has no bonding at all.

 

Maybe you could first print this in PLA until you get that right? And only then move to more difficult materials? There are a lot of variables and design-features that might need fine-tuning: to get your overhangs smooth instead of rough, to get the gap between support and print right for easy removal, to get the bonding right, and to fight the warping.

 

[stan_bulgaria 4]

Hello Geert,

 

thank you for your support. A good news - I have finally made it the way I wanted.

 

It took a lot of trials and research on the forums but the result is accomplished. Here is how.

 

First I have to admit I made a simple mistake. When I read, you guys are using glass I didn't pay attention what kind of glass. With Creality Ender 3 V2 the bed platform comes with glass that is coated with some special, probably paint. It stays on the top side of the glass and you extrude over it. With PLA it bonds very good - no need of anything additional glues. So I read about the salt water method, the wood adhesive and so on, but didn't pay attention that you put all that on glass. And by glass you all have meant bear glass. 🙂 I did the trial with the salted water on the coated side of the glass and it was disaster (I tried it although it was written "working with PLA only"). Then went back on reading in the forums and I realized the mistake I was doing. So I turned the glass with the uncoated side up and sprayed it with hair spray. This time it worked. Beautifully, smooth working.

 

Nozzle T=225C

Bed T=75C

Fan 205 rpm

 

For the raft

Nozzle T=240C

Bed T-75C

Fan 0 rpm

 

Room temperature 19-20 C; humidity = 47-51%.

 

I did this without filament drying!

 

Thanks for the help of all of you guys.

 

[Torgeir 242]

Hi Stan,

 

That's great news, way to go!

 

Thanks for the feedback.

 

Torgeir